Experimental Determination of Impurity
and Interdiffusion Coefﬁcients in Seven Ti and Zr
Binary Systems Using Diffusion Multiples
ZHANGQI CHEN, ZI-KUI LIU, and JI-CHENG ZHAO
Diﬀusion coeﬃcients of seven binary systems (Ti-Mo, Ti-Nb, Ti-Ta, Ti-Zr, Zr-Mo, Zr-Nb, and
Zr-Ta) at 1200 °C, 1000 °C, and 800 °C were experimentally determined using three
Ti-Mo-Nb-Ta-Zr diﬀusion multiples. Electron probe microanalysis (EPMA) was performed
to collect concentration proﬁles at the binary diﬀusion regions. Forward simulation analysis
(FSA) was then applied to extract both impurity and interdiﬀusion coeﬃcients in Ti-rich and
Zr-rich part of the bcc phase. Excellent agreements between our results and most of the
literature data validate the high-throughput approach combining FSA with diﬀusion multiples
to obtain a large amount of systematic diﬀusion data, which will help establish the diﬀusion
(mobility) databases for the design and development of biomedical and structural Ti alloys.
Ó The Minerals, Metals & Materials Society and ASM International 2018
number of hip and knee arthroplasties in the
United States has surged over the past decade and is
projected to increase to 3.5 million procedures a year by
The rising demand signiﬁes the importance of
structural biomaterials in clinical applications, especially
for bone replacement and fastening surgeries. In recent
years, Ti alloys have been widely used as implants due to
their low elastic moduli, outstanding biocompatibility,
and good corrosion resistance in comparison with
stainless steels and Cobalt-based alloys.
exhibit a phase transformation between the low tem-
perature a (hcp) phase and the high temperature b (bcc)
phase. Compared to a and a + b type Ti alloys, b type
Ti alloys are more attractive for biomedical implant
applications due to their lower elastic moduli.
additional advantages like high strengthening eﬀect and
non-toxicity, alloying elements Mo, Nb, Ta, and Zr
have been frequently added in recent years.
type Ti alloys with additions of these elements can
achieve low elastic modulus such as Ti-24Nb-4Zr-7.9Sn
) and Ti-35Nb-Ta-Zr (61 GPa
), which is
getting close to match that of bones (~ 10 to 30 GPa).
The elastic modulus mismatch between the bio-implants
and bones often leads to ‘‘stress shielding’’ which is one
of the key mechanisms of implant failure.
It is thus
highly desirable to engineer the elastic modulus of
biocompatible Ti alloys to match that of bones.
This study is part of a project funded by the DMREF
(Designing Materials to Revolutionize and Engineer our
Future) program of the U.S. National Science Founda-
tion to establish a knowledge base of thermodynamics,
kinetics, and elastic properties of the Ti-Mo-Nb-Ta-Zr
system for the accelerated development of Ti alloys for
biomedical implant applications.
Diﬀusion multiples integrate several diﬀusion couples
and diﬀusion triples into high-throughput samples.
High temperature diﬀusion annealing creates wide
composition ranges for the associated binary and
ternary systems from which composition-dependent
material properties can be obtained.
In this study,
three Ti-Mo-Nb-Ta-Zr diﬀusion multiples were made
and heat treated at 800 °C, 1000 °C, and 1200 °C from
which large amounts of phase equilibria, kinetics, and
composition-dependent property information will be
obtained. This article reports the impurity and interdif-
fusion coeﬃcients of seven Ti- and Zr-containing binary
It is noted that even though our study is intended for
the biomedical Ti alloy development. The diﬀusion
coeﬃcients of the Ti-Mo-Nb-Ta-Zr system are also
valuable parameters for the design of structural Ti alloys
and refractory high entropy (multi-principal element)
ZHANGQI CHEN and JI-CHENG ZHAO are with the
Department of Materials Science and Engineering, The Ohio State
University, Columbus, OH 43210. Contact e-mail: firstname.lastname@example.org
ZI-KUI LIU is with the Department of Materials Science and
Engineering, The Pennsylvania State University, University Park, PA
Manuscript submitted December 5, 2017.
Article published online May 1, 2018
3108—VOLUME 49A, JULY 2018 METALLURGICAL AND MATERIALS TRANSACTIONS A